1. Field of the Invention
The present invention relates to a stereoscopic-image display device that allows an observer to perceive a stereoscopic image by displaying a parallax image.
2. Description of the Related Art
Since one eye of a human is about several centimeters away from the other eye, there is an offset in position between an image perceived by a right eye and an image perceived by a left image. A human brain perceives depth by using the offset in position as one of guides. Oppositely speaking, pseudo-perception of depth by a brain can be realized by providing an offset in position between respective images to be perceived by both eyes. Various methods that allow a brain to recognize a plane image as a stereoscopic image by using the binocular parallax are in practical use. The methods are divided broadly into stereoscopic technology including shutter glasses technology, polarizing glasses technology, anaglyph glasses technology, etc., and autostereoscopic technology including parallax—barrier technology, lenticular lens technology, etc.
Due to the principle of a stereoscopic-image display device that a stereoscopic image is perceived by using binocular parallax, there is a problem that, even when a same parallax image is used, a natural stereoscopic image cannot be obtained if the size of a picture plane that displays the parallax image is different. To cope with this problem, a technique of acquiring size information of a display picture plane of a stereoscopic video image, which is set in association with the stereoscopic video image, and setting the offset between a left-eye video image and a right-eye video image based on the information so as to adjust the stereoscopic effect of the video image to be displayed.
In recent years, projectors that can reproduce stereoscopic video images have been developed. Due to a feature of projecting a video image onto a projection plane such as a screen, the size of a picture plane of a projector varies according to the environment. Therefore, when the size of the picture plane is not specified as in the case of a projector, it is considered that size information of a display picture plane is not prepared.
In this background, a purpose of the present invention is to provide a stereoscopic-image displaying technique of displaying a stereoscopic image having the optimal amount of display parallax regardless of the size of a display picture plane.
One embodiment of the present invention provides a stereoscopic-image display device that projects a stereoscopic image on a projection plane and displays the stereoscopic image. The device comprises: a projection unit configured to superimpose, on a predetermined display area, a parallax image formed of a first image and a second image having predetermined parallax relative to the first image so as to project and display the parallax image; and a display size determination unit configured to determine whether or not the size of a display area in the projection plane at least an upper-limit size that is determined based on the threshold value of the amount of parallax that allows the parallax image to be perceived as a stereoscopic image.
Optional combinations of the aforementioned constituting elements, and implementations of the invention in the form of methods, apparatuses, and systems may also be practiced as additional modes of the present invention.